1. Field of the Invention
The present invention relates to a perpendicular magnetic write head provided with a magnetic pole and a write shield, and a magnetic recording device incorporating the head.
2. Description of the Related Art
Due to the recent increase of the areal recording density of a magnetic recording medium (hereinafter, referred to as “recording medium”) typified by a hard disk, there is a demand for the better performance capabilities of a magnetic write head. In order to meet such a demand, as an alternative to the longitudinal magnetic recording mode that has been the recording mode for the magnetic write head, the perpendicular magnetic recording mode is now receiving attention. With the longitudinal magnetic recording mode, the direction of a signal magnetic field is set to be in the in-plane direction of a recording medium, and with the perpendicular magnetic recording mode, the direction thereof is set to intersect with the plane thereof. This is due to advantages of a higher linear recording density, and less susceptibility to thermal fluctuations for any recording medium completed with recording.
A magnetic write head of such a perpendicular magnetic recording mode (hereinafter, referred to as “perpendicular magnetic write head”) is provided with a main magnetic-pole layer for use to direct, to a recording medium, any magnetic fluxes generated by a thin-film coil. This main magnetic-pole layer includes a tip end portion (magnetic pole) of a very narrow width for generation of a magnetic field (perpendicular magnetic field) for recording use through emission of the magnetic fluxes.
As to the configuration of such a perpendicular magnetic write head, various different studies have been in progress for the purpose of increasing the perpendicular magnetic field in intensity and gradient, for example.
In a specific configuration, for an increase of the gradient of the magnetic field in a direction intersecting a track-width direction (cross-track direction), i.e., down-track direction, a first soft magnetic film is provided. The first soft magnetic film is narrow in width, and is disposed between a main magnetic pole also narrow in width and a second soft magnetic film wide in width. The first soft magnetic film is coupled to the second soft magnetic film with a distance from the main magnetic pole via a first non-magnetic film (an example includes Japanese Unexamined Patent Publication No. 2007-035082). This configuration also includes a pair of third soft magnetic films for an increase of the gradient of the magnetic field in the cross-track direction. These third soft magnetic films are disposed respectively on both sides of the main magnetic pole in the cross-track direction with a distance therefrom each via a second non-magnetic film.
For protection of any recorded signals from possible deletion or others by any leakage magnetic field, the narrow tip end portion is located via a gap on the trailing side of a main magnetic pole together with an auxiliary magnetic pole wide in width. The auxiliary magnetic pole is being inserted with a non-magnetic layer (an example includes Japanese Unexamined Patent Publication No. 2004-326990).
For reduction of any magnetic field being a cause of noise generation in a recording medium, first and second shield layers are provided on the trailing side of a recording pole. These first and second shield layers are so disposed as to be away from the recording pole via an insulation layer on the side closer to an air bearing surface, and to be coupled to the recording pole on the side away from the air bearing surface (an example includes Japanese Patent No. 4044922).
For reduction of any leakage magnetic field, a narrow laminate is provided between first and second poles, which are both narrow in width (an example includes Japanese Unexamined Patent Publication No. 2004-234830). This laminate includes an insulation medium inserted into an anisotropic medium having the magnetic anisotropy.
As a related technology, in a longitudinal magnetic write head, for prevention of blurring in writing and for achievement of satisfactory overwriting, a narrow laminate is provided between upper and lower magnetic poles, which are both wide in width (an example includes U.S. Pat. No. 6,624,972). This laminate includes a lower sub magnetic pole, a first non-magnetic film, a soft magnetic film, a second non-magnetic film, and an upper sub magnetic pole, which are laminated in order from the side closer to the lower magnetic pole.
The concern here is that the areal recording density of a recording medium is increasing all the more, and thus the development work has been in progress for a perpendicular magnetic write head that may keep up with the increase of the areal recording density. However, increasing the intensity of a perpendicular magnetic field is in a relationship of trade-off with increasing the gradient thereof, and such an attempt is difficult to be achieved.
As such, achieving such an attempt of increasing the intensity and gradient of a perpendicular magnetic field at the same time is very much expected.